1. FIELD OF THE INVENTION
The invention relates to an improved multi-level conductor electrode structure for VLSI circuits and to the method of forming the improved structure. The multi-level conductor electrode structure is formed using an air dielectric between the conductor electrode levels. The conductor electrodes and the interconnecting inter-level metal studs are coated with a thin envelope oxide. The entire structure is covered with a passivation layer having poor step coverage.
2. DESCRIPTION OF THE RELATED ART
The conventional fabrication of multi-level conductor electrode metal structures uses levels of conductor electrode metal and inter-metal dielectric stacked layer by layer until the desired number of conductor levels are formed. In this invention the inter-level dielectric is replaced by air dielectric thereby reducing parasitic capacitance and improving circuit performance. This invention uses a thin envelope oxide coating on all metal electrodes and inter-metal studs.
There are other patents dealing with air gap isolation. U.S. Pat. No. 5,216,537 to Hornbeck shows a method for making air gap isolation in circuit metalization. U.S. Pat. No. 4,169,000 to Riseman, U.S. Pat. No. 4,710,794 to Koshino et al, and U.S. Pat. No. 5,227,658 to Beyer et al show methods for making air gap isolation between segments of the integrated circuit.